TW201625803A - Ag alloy sputtering target, method for producing Ag alloy sputtering target, Ag alloy film, and method for producing ag alloy film - Google Patents

Abstract

The Ag alloy sputtering target of the present invention includes 0.1 to 3.0 at% of Sn, 1.0 to 10.0 at% of Cu, and the balance consisting of Ag and the inevitable impurities. The Ag alloy film of the present invention includes 0.1 to 3.0 at% of Sn, 1.0 to 10.0 at% of Cu, and the balance consisting of Ag and the inevitable impurities.

Description

Ag alloy sputtering target, method for producing Ag alloy sputtering target, method for manufacturing Ag alloy film and Ag alloy film

The present invention relates to an Ag alloy sputtering target for forming an Ag alloy film which can be applied to, for example, a transparent conductive film for a display or a touch panel or a metal thin film for an optical functional film, and a method for producing an Ag alloy sputtering target, A method for producing an Ag alloy film and an Ag alloy film.

Priority is claimed on Japanese Patent Application No. 2014-190278, filed on Sep. .

Generally, a patterned transparent conductive film is widely used in electronic devices such as touch panels, solar cells, and organic EL devices. Ag or an Ag alloy in which an element is added to Ag has excellent conductivity, and excellent transmittance can be obtained in thin film formation. Therefore, application of a transparent conductive film of such an electronic device can be expected (refer to Patent Document 1). ).

Further, in the field of hot wire cutting or display devices, although an optical functional film is used, it is known that the optical functional film is formed by a high refractive index film formed of a metal oxide and a metal film alternately laminated on a transparent polymer. A transparent laminated film called a multilayer film type formed on one side of a film. Ag or an Ag alloy is also used as the material of the metal thin film of the optical functional film (see Patent Document 2).

However, Ag and Ag alloys have problems such as deterioration of characteristics due to corrosion of moisture, sulfur, and the like in the manufacturing process and the environment in use, and are liable to cause changes in film appearance (spots, etc.), such as film thickness for semi-permeable membranes. (15 nm or less) These are particularly noticeable, and the occurrence of speckles due to adhesion of the particles to the surface of the film is also a problem.

Therefore, Patent Document 3 and Patent Document 4 propose an Ag alloy film which improves environmental resistance.

Patent Document 3 proposes an Ag alloy film in which a noble metal such as platinum, palladium, gold, rhodium, ruthenium or iridium is added to Ag.

Further, Patent Document 4 proposes an Ag alloy film containing Bi and containing at least one selected from the group consisting of Zn, Al, Ga, In, Si, Ge, and Sn.

[Previous Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 07-114841

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2006-328353

[Patent Document 3] Japanese Re-publication WO2006/132413

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2005-332557

However, in the Ag alloy film described in Patent Document 3, since a noble metal is used as an additive element, there is a disadvantage that the material cost is high.

Further, in the Ag alloy film described in Patent Document 4, the absorption rate is high and the optical characteristics are insufficient.

In particular, recently, it has been demanded to further improve the visual transmittance of the above-mentioned transparent conductive film and the metal thin film of the optical functional film, which is not compatible with the conventional Ag alloy film. Further, excellent conductivity (electrical characteristics) is required for a transparent conductive film used in an electronic device such as an organic EL device.

The present invention has been made in view of the above problems, and an object thereof is to provide an Ag alloy sputtering target, an Ag alloy sputtering target manufacturing method, and an Ag alloy film which are excellent in film forming electrical properties, optical properties, and environmental resistance. And a method of producing an Ag alloy film.

In order to solve the problem, the Ag alloy sputtering target according to the first aspect of the present invention is characterized in that it contains Sn in a range of 0.1 at% or more and 3.0 at% or less, and contains Cu in a range of 1.0 at% or more and 10.0 at% or less. The rest consists of Ag and unavoidable impurities.

The Ag alloy sputtering target according to the first aspect of the present invention contains Sn in a range of 0.1 at% or more and 3.0 at% or less, and Cu in a range of 1.0 at% or more and 10.0 at% or less. In part, it consists of Ag and unavoidable impurities, so that aggregation of Ag can be suppressed, and an Ag alloy film which greatly improves environmental resistance can be formed. Further, by containing Sn, it is possible to suppress deterioration of optical characteristics of the Ag alloy film in a hot humid environment. Further, by containing Cu, it is possible to suppress deterioration of electrical characteristics of the Ag alloy film in a hot humid environment.

In the Ag alloy sputtering target according to the first aspect of the present invention, the total content of Na, Si, V, Cr, Fe, and Co is preferably 100 ppm by mass or less in the unavoidable impurities.

In this case, since the total content of Na, Si, V, Cr, Fe, and Co of the element having a small solid-solidity to Ag among the unavoidable impurities is limited to 100 ppm by mass or less, the elements can be suppressed. Segregation at the grain boundary prevents the occurrence of abnormal discharge during sputtering.

Further, in the Ag alloy film formed, it is possible to suppress the segregation of these elements at the grain boundary, and it is possible to suppress the deterioration of the environmental resistance of the Ag alloy film.

Further, in the Ag alloy sputtering target according to the first aspect of the present invention, among the unavoidable impurities, the content of each of Na, Si, V, Cr, Fe, and Co is preferably 30 ppm by mass or less.

In this case, since the content of each element of Na, Si, V, Cr, Fe, and Co, which is an element having a small solid-melt degree for Ag, is limited to 30 ppm by mass or less, abnormal discharge can be surely prevented from occurring during sputtering. Further, in the Ag alloy film formed into a film, it is possible to surely suppress the decrease in environmental resistance.

Further, in the Ag alloy sputtering target according to the first aspect of the present invention, the average crystal grain size of the sputtering surface is preferably 200 μm or less, and further, the particle size of the segregation portion formed of Cu, Sn or the intermetallic compound is used. Not reached 1 μm.

In this case, since the average crystal grain size is 200 μm or less, it is possible to reduce the unevenness due to the difference in the sputtering rate due to the crystal orientation when the sputtering surface is sputtered, and it is possible to suppress the occurrence of abnormal discharge.

Further, since the particle diameter of the segregation portion made of Cu, Sn or the intermetallic compound is less than 1 μm, the sputtering rate and the composition of the component in the Ag alloy film formed can be stabilized during the long-time sputtering. Moreover, the segregation portion is better not present in the tissue.

Further, in the Ag alloy sputtering target according to the first aspect of the present invention, Ti is further contained in a range of 0.1 at% or more and 3.0 at% or less.

In this case, since 0.1 atom% or more of Ti is added, the resistance of the formed Ag alloy film to chemicals can be greatly improved. In addition, since the amount of addition of Ti is limited to 3.0 at% or less, deterioration of optical characteristics and electrical characteristics of the Ag alloy film formed by the film can be suppressed.

The method for producing an Ag alloy sputtering target according to the second aspect of the present invention is the above-mentioned Ag alloy sputtering target (having a content of Sn in a range of 0.1 at% or more and 3.0 at% or less, and a range of 1.0 at% or more and 10.0 at% or less. Cu is contained therein, and the remainder is composed of Ag and unavoidable impurities, and the average crystal grain size of the sputtered surface is 200 μm or less, and further, the segregation portion of Cu, Sn or the intermetallic compound is formed. A method for producing an Ag alloy sputtering target having a diameter of less than 1 μm, characterized in that it has a melt casting step of forming an Ag alloy ingot, a rolling step of rolling the obtained Ag alloy ingot, and a heat treatment after rolling a heat treatment step in which the heat treatment temperature in the aforementioned heat treatment step is 650 ° C or higher and 750 ° C Within the scope below.

According to the method for producing an Ag alloy sputtering target having the above configuration, since the heat treatment temperature in the heat treatment step is 650 ° C or higher, Cu, Sn diffusion and digestion segregation can be eliminated, and Cu, Sn or the like intermetallic compound can be obtained. The resulting segregation unit becomes smaller. Further, since the heat treatment temperature in the heat treatment step is 750 ° C or lower, coarsening of crystal grains can be suppressed.

The Ag alloy film according to the third aspect of the present invention is characterized in that it contains Sn in a range of 0.1 at% or more and 3.0 at% or less, Cu in a range of 1.0 at% or more and 10.0 at% or less, and the balance is Ag and Avoid the composition of impurities.

The Ag alloy film having such a composition contains Sn in a range of 0.1 at% or more and 3.0 at% or less, and contains Cu in a range of 1.0 at% or more and 10.0 at% or less, and the remainder is composed of Ag and unavoidable impurities. The composition is excellent in electrical properties, environmental resistance, and optical properties, and is particularly suitable as a metal thin film of a transparent conductive film or an optical functional film.

In the Ag alloy film according to the third aspect of the present invention, the visual transmittance is preferably 70% or more, and the visual absorptivity is 10% or less.

In this case, the visibility is excellent, and it can be suitably used as a metal thin film of a transparent conductive film or an optical functional film of various displays or touch panels.

In the Ag alloy film of the third aspect of the invention, the sheet resistance value is preferably 40 Ω/□ or less.

In this case, it can be used as a transparent conductive film excellent in electrical conductivity. In an electrode film or wiring film of a display or a touch panel.

In the Ag alloy film of the third aspect of the invention, the film thickness is preferably in the range of 4 nm or more and 10 nm or less.

In this case, since the thickness of the Ag alloy film is 4 nm or more, the electric resistance can be surely lowered, and conductivity can be ensured. Further, since the thickness of the Ag alloy film is 10 nm or less, the visual transmittance can be surely improved.

A method of producing an Ag alloy film according to a fourth aspect of the present invention is characterized in that the film formation is carried out by using the Ag alloy sputtering target in the above-described first state.

According to the method for producing an Ag alloy film having such a configuration, an Ag alloy film containing Cu and Sn and having excellent electrical properties, environmental resistance, and optical properties can be formed.

According to the present invention, it is possible to provide an Ag alloy sputtering target, an Ag alloy sputtering target manufacturing method, an Ag alloy film, and an Ag alloy film manufacturing method of an Ag alloy film which are excellent in film forming electrical properties, optical properties, and environmental resistance.

1 is a photograph of the structure of an Ag alloy sputtering target of the embodiment. (a) is an Ag alloy sputtering target of Example 1 of the present invention, and (b) is an Ag alloy sputtering target of Example 26 of the present invention.

2 is an appearance of an Ag alloy film after constant temperature and humidity test of the embodiment. Observation results. (a) is judged as "A", and (b) is judged as "B".

Hereinafter, an Ag alloy sputtering target and an alloy film according to an embodiment of the present invention will be described.

The Ag alloy sputtering target of the present embodiment is used when forming an Ag alloy film. Here, the Ag alloy film of the present embodiment is a metal thin film which is a transparent conductive film or an optical functional film of an electronic device such as a touch panel, a solar cell or an organic EL device.

<Ag alloy sputtering target>

In the Ag alloy sputtering target of the present embodiment, Sn is contained in a range of 0.1 at% or more and 3.0 at% or less, and Cu is contained in a range of 1.0 at% or more and 10.0 at% or less, and the balance is inevitable. It is composed of an Ag alloy composed of impurities.

Further, in the present embodiment, the total content of Na, Si, V, Cr, Fe, and Co in the unavoidable impurities is 100 ppm by mass or less. Further, the content of Na, Si, V, Cr, Fe, and Co in the unavoidable impurities is 30 ppm by mass or less. Further, Ti may be contained in a range of 0.1 at% or more and 3.0 at% or less, as needed.

Further, in the Ag alloy sputtering target of the present embodiment, the average crystal grain size of the sputtering surface is 200 μm or less, and the particle diameter of the segregation portion made of Cu, Sn or the intermetallic compound is less than 1 μm.

Hereinafter, the reason for specifying the composition and crystal structure of the Ag alloy sputtering target of the present embodiment will be described.

(Sn: 0.1 atom% or more and 3.0 atom% or less)

Sn is an element having an effect of improving the environmental resistance of the Ag alloy film formed. In particular, it has an effect of effectively suppressing a decrease in optical characteristics in a hot humid environment.

Here, when the content of Sn in the Ag alloy sputtering target is less than 0.1 atom%, the above-described effects may not be sufficiently exhibited. On the other hand, when the Sn content in the Ag alloy sputtering target exceeds 3.0 atom%, the electrical characteristics of the film-formed Ag alloy film are lowered.

For this reason, in the present embodiment, the Sn content in the Ag alloy sputtering target is set to be in the range of 0.1 at% or more and 3.0 at% or less. In order to achieve the above-described effects, the lower limit of the Sn content in the Ag alloy sputtering target is preferably 0.4 atom% or more, and the upper limit is 2.0 atom% or less.

(Cu: 1.0 atom% or more and 10.0 atom% or less)

The Cu-based element has an effect of improving the environmental resistance of the Ag alloy film formed into a film. In particular, it has an effect of effectively suppressing a decrease in electrical characteristics in a hot humid environment. Further, it has an effect of suppressing the occurrence of spots or the like in the Ag alloy film formed in the film in a hot humid environment.

Here, when the content of Cu in the Ag alloy sputtering target is less than 1.0 atom%, the above-described effects may not be sufficiently exhibited. On the other hand, Ag When the Cu content in the alloy sputtering target exceeds 10.0 atom%, the electrical characteristics of the film-formed Ag alloy film may be lowered. Further, there is a possibility that the absorption rate of the Ag alloy film formed by the film is increased to lower the optical characteristics.

For this reason, in the present embodiment, the Cu content in the Ag alloy sputtering target is set to be in the range of 1.0 at% or more and 10.0 at% or less. In order to achieve the above-described effects, the lower limit of the Cu content in the Ag alloy sputtering target is preferably 2.0 atom% or more, and the upper limit is 8.0 atom% or less.

(Na, Si, V, Cr, Fe, Co: the total content is 100 ppm by mass or less, and each content is 30 ppm by mass or less)

Among the unavoidable impurities, the elements of Na, Si, V, Cr, Fe, and Co are segregated at the crystal grain boundary of the Ag alloy sputtering target due to the small solid solubility for Ag, and react with oxygen to form an oxide. Due to the presence of oxides in the Ag alloy sputtering target, abnormal discharge and splash are generated during sputtering. Moreover, elements such as Na, Si, V, Cr, Fe, and Co are also prone to segregation at the grain boundary in the Ag alloy film formed. In a hot humid environment, these elements are oxidized to lower the crystallinity of the Ag alloy film. And there is a reduction in environmental resistance.

For the reason of the above, in the Ag alloy sputtering target of the present embodiment, the total content of Na, Si, V, Cr, Fe, and Co in the unavoidable impurities is limited to 100 ppm by mass or less. Further, in order to suppress the number of abnormal discharges, in the present embodiment, the content of Na, Si, V, Cr, Fe, and Co in the unavoidable impurities is limited to 30 ppm by mass or less. also, The total content of Na, Si, V, Cr, Fe, and Co elements in the unavoidable impurities is preferably 20 ppm by mass or less. Further, it is preferred that the content of the Na, Si, V, Cr, Fe, and Co elements in the unavoidable impurities be 10 ppm by mass or less.

(Ti: 0.1 atom% or more and 3.0 atom% or less)

Improve chemical resistance by adding Ti. Specifically, the sulfur resistance and chlorine resistance of the Ag alloy film formed can be improved.

Here, when the content of Ti is less than 0.1 atom%, there is a possibility that the above-described effects cannot be sufficiently exhibited. On the other hand, when the Ti content exceeds 3.0 at%, the optical properties and electrical properties of the formed Ag alloy film are deteriorated.

For this reason, in the present embodiment, when Ti is added, the content of Ti is set to be in the range of 0.1 at% or more and 3.0 at% or less.

(The average crystal grain size of the sputtered surface: 200 μm or less)

Since the sputtering target differs depending on the crystal orientation, irregularities are generated on the sputtering surface at the sputtering surface due to the crystal grains due to the difference in sputtering. Here, when the average crystal grain size in the sputtering surface exceeds 200 μm, the unevenness generated on the sputtering surface becomes large, and electric charges are concentrated on the convex portion, and abnormal discharge is likely to occur.

For these reasons, in the Ag alloy sputtering target of the present embodiment, the average crystal grain size of the sputtering surface is set to 200 μm or less.

Further, in order to suppress the occurrence of abnormal discharge on the sputtering surface during sputtering, it is preferable to set the average crystal grain size of the sputtering surface to 150 μm. Next, it is better to set it to 80 μm or less. Further, the lower limit of the average crystal grain size is not particularly limited, but is preferably 30 μm, more preferably 50 μm.

Here, in the present embodiment, samples of a square body having a side of about 10 mm were sampled from 16 positions in the sputtering surface, and the average crystal grain size was measured. Specifically, the target was divided into 16 portions of 4×width 4 and sampled from the central portion of each portion. Further, in the present embodiment, a sampling method of a sample of a rectangular target which is generally used as a large-sized target is described. However, the present invention is of course effective in suppressing the occurrence of splashing of a circular target. At this time, according to the sampling method of the large rectangular target sample, the sputtered surface of the target was divided into 16 equal places, and sampling was performed.

(particle size of segregation portion made of Cu, Sn or these intermetallic compounds: less than 1 μm)

Ag alloy sputtering target containing Sn in a range of 0.1 at% or more and 3.0 at% or less, Cu in a range of 1.0 at% or more and 10.0 at% or less, and the balance being composed of Ag and unavoidable impurities Among them, there is a case where a segregation portion made of Cu, Sn or an intermetallic compound is present. When the particle diameter of the segregation portion is 1 μm or more, the sputtering rate at the time of long-term sputtering becomes unstable, and the composition of the Ag alloy film to be formed may vary.

For the reason of the above, in the Ag alloy sputtering target of the present embodiment, the particle diameter of the segregation portion made of Cu, Sn or the intermetallic compound is set to be less than 1 μm.

Also, in order to make the sputtering rate for a long time of sputtering, it is really stable, and indeed Since the composition variation of the Ag alloy film formed by the film is suppressed, the segregation portion made of Cu, Sn or the intermetallic compound is preferably not present in the structure.

<Method of Manufacturing Ag Alloy Sputtering Target>

Next, a method of manufacturing the Ag alloy sputtering target of the present embodiment will be described.

First, Ag having a purity of 99.9% by mass or more and Cu and Sn having a purity of 99.9% by mass or more are prepared as a melting raw material. Moreover, when Ti is added, Ti having a purity of 99.9% by mass or more is prepared.

Here, in order to surely reduce the content of Na, Si, V, Cr, Fe, and Co in the unavoidable impurities, the elements contained in the Ag raw material are analyzed by ICP analysis or the like, and used for screening. Further, in order to surely reduce the content of Na, Si, V, Cr, Fe, and Co in the unavoidable impurities, it is preferred to immerse the Ag raw material in nitric acid, sulfuric acid, or the like, and then perform electrolytic refining using an electrolytic solution having a specific Ag concentration.

The Ag raw material to be screened and the Cu raw material and the Sn raw material are weighed in a specific composition. Next, in the melting furnace, Ag is melted in a high vacuum or an inert gas atmosphere, and a specific content of Cu and Sn, optionally Ti, is added to the obtained melt. Subsequently, it is melted in a vacuum or an inert gas atmosphere to have Sn in a range of 0.1 at% or more and 3.0 at% or less, and Cu in a range of 1.0 at% or more and 10.0 at% or less, and 0.1 atom% or more and 3.0 atoms. In the range below %, the Ti is optionally contained, and the remainder is Ag alloy ingots formed by Ag and unavoidable impurities (melting casting step).

Next, the obtained Ag alloy ingot was subjected to cold rolling (rolling step). The rolling ratio in the rolling step is preferably in the range of 60% or more and 80% or less.

Next, heat treatment (heat treatment step) is performed after the rolling. The heat treatment temperature in this heat treatment step is set to be in the range of 650 ° C to 750 ° C. Further, the holding time at the heat treatment temperature is preferably in the range of 60 minutes or more and 180 minutes or less.

Subsequently, the Ag alloy sputtering target of the present embodiment was produced by mechanical processing. Further, the shape of the Ag alloy sputtering target is not particularly limited, and may be a disk type, a gusset type, or a cylindrical type.

<Ag alloy film>

The Ag alloy film of the present embodiment is formed by using the Ag alloy sputtering target of the above-described embodiment, and has the same composition as that of the Ag alloy sputtering target.

As an optical characteristic of the Ag alloy film, the visual transmittance in the visible light region is 70% or more, and the visual absorptance is 10% or less.

As for the electrical characteristics of the Ag alloy film, the sheet resistance value is set to 40 Ω/□ or less.

Further, in the Ag alloy film of the present embodiment, the film thickness is in the range of 4 nm or more and 10 nm or less.

Here, when the thickness of the Ag alloy film is less than 4 nm, there is a possibility that electrical characteristics cannot be maintained. Further, since the film is easily aggregated, the environmental resistance is lowered. On the other hand, when the film thickness of the Ag alloy film exceeds 10 nm, there is a suction. The optical properties such as yield are lowered.

For this reason, in the present embodiment, the film thickness of the Ag alloy film is set to be in the range of 4 nm or more and 10 nm or less. Further, the lower limit of the film thickness of the Ag alloy film is preferably 6 nm or more, and the upper limit of the film thickness of the Ag alloy film is preferably 8 nm or less.

When the Ag alloy film of the present embodiment is formed into a film, a magnetron sputtering method is preferably used, and the power source can be selected from a direct current (DC) power source, a high frequency (RF) power source, an intermediate frequency (MF) power source, and an alternating current (AC) power source. Any one.

As the substrate to be formed, a glass plate or foil, a metal plate or foil, a resin plate or a resin film or the like can be used. Further, the arrangement of the substrate at the time of film formation may be a static alignment method or a wiring method.

According to the Ag alloy sputtering target of the present embodiment, the composition contains Sn in a range of 0.1 at% or more and 3.0 at% or less, and Cu in a range of 1.0 at% or more and 10.0 at% or less. Since it is composed of Ag and unavoidable impurities, it is possible to form an Ag alloy film which greatly improves environmental resistance. Specifically, it is possible to suppress a decrease in optical characteristics and electrical characteristics of the Ag alloy film in a hot humid environment.

Further, according to the Ag alloy sputtering target of the present embodiment, the total content of Na, Si, V, Cr, Fe, and Co of the element having a small solid solubility to Ag is limited to 100 mass due to unavoidable impurities. When the amount is less than ppm, it is possible to suppress the segregation of these elements at the crystal grain boundary to form an oxide, and it is possible to suppress the occurrence of abnormal discharge or splash during sputtering.

Moreover, the Ag alloy film formed can also inhibit the crystallization of these elements. Segregation at the grain boundary suppresses deterioration of the environmental resistance of the Ag alloy film.

Further, in the Ag alloy sputtering target of the present embodiment, since the content of each of Na, Si, V, Cr, Fe, and Co in the unavoidable impurities is 30 ppm by mass or less, it is possible to surely suppress the abnormality at the time of sputtering. Discharge and splashing occur. Further, the film formation of the Ag alloy film can also suppress the decrease in the environmental resistance of the Ag alloy film.

The Ag alloy film of the present embodiment is formed by using the Ag alloy sputtering target of the above-described embodiment, and has the same composition as that of the Ag alloy sputtering target of the present embodiment, so that electrical properties, environmental resistance, and optical properties are obtained. Excellent, especially suitable as a metal film for a transparent conductive film or an optical functional film.

Specifically, the optical transmittance is 70% or more, and the visual absorptivity is 10% or less. Therefore, the Ag alloy film of the present embodiment can be used as the permeable film excellent in visibility.

In addition, since the sheet resistance is 40 Ω/□ or less as the electrical characteristics, the Ag alloy film of the present embodiment can be used as a conductive film having excellent conductivity.

Further, in the Ag alloy film of the present embodiment, since the film thickness is set to be in the range of 4 nm or more and 10 nm or less, aggregation of the film can be suppressed and environmental resistance can be ensured. Moreover, electrical characteristics and optical characteristics can be ensured.

The embodiments of the present invention have been described above, but the present invention is not limited thereto, and can be appropriately modified without departing from the spirit of the invention.

For example, the present embodiment is used as, for example, a touch panel or solar power. A transparent conductive film of an electronic device such as a cell or an organic EL device, or a metal thin film of an optical functional film will be described. However, the present invention is not limited thereto and may be used for other purposes.

In addition, the film thickness of the Ag alloy film is not limited to this embodiment, and may be appropriately changed depending on the intended use.

[Examples]

Hereinafter, the results of the confirmation experiment for confirming the validity of the present invention will be described.

<Sputter target for forming an Ag alloy film>

First, Ag, a purity of 99.9% by mass or more, and Cu, Sn, and Ti having a purity of 99.9% by mass or more are prepared as a melting raw material. Here, in order to reduce the content of each impurity, a method in which an Ag raw material is immersed in nitric acid or sulfuric acid or the like and then electrolytically purified using an electrolytic solution having a specific Ag concentration is used. The Ag raw material which reduces the impurities by the purification method is subjected to impurity analysis by the ICP method, and the total concentration (content) of Na, Si, V, Cr, Fe, and Co is 100 ppm by mass or less and the concentration of each element. A 30 ppm Ag raw material was used as a raw material for the sputtering target.

The amount of the Ag raw material to be screened and the added Cu, Sn, and Ti are measured in a specific composition. Next, Ag is melted in a high vacuum or an inert gas atmosphere, and Cu, Sn, and Ti are added to the obtained Ag melt, and melted in a vacuum or an inert gas atmosphere. Subsequently, the solution was poured into a mold to manufacture an Ag alloy ingot. Here, Ag is melted in an atmosphere in which the atmosphere is once vacuumed (5 × 10 ^-2 Pa or less) and then replaced with Ar gas. Further, the addition of Cu, Sn, and Ti was carried out in an Ar gas atmosphere.

Next, the obtained Ag alloy ingot was subjected to cold rolling at a reduction ratio of 70%.

Subsequently, heat treatment was maintained for 1 hour in the atmosphere at the temperatures shown in Table 2. Next, an Ag alloy sputtering target having a diameter of 152.4 mm and a thickness of 6 mm was produced by mechanical processing.

Further, in the Ag alloy sputtering target of Examples 8 to 16 of the present invention, each element of Na, Si, V, Cr, Fe, and Co was added in an appropriate amount at the time of melting. Further, in the Ag alloy sputtering target of Examples 20 to 23, 30, and 31 of the present invention, an Ag raw material which was not subjected to electrolytic refining and screening of the Ag alloy was used.

(composition analysis)

A sample for analysis of the Ag alloy ingot after casting was sampled, and the sample was analyzed by ICP emission spectrometry. The results of the analysis are shown in Table 1.

(crystal size)

The sputtered surface of the obtained Ag sputter target was divided into 8 equal portions by a line dividing the center thereof, and a sample piece was sampled from the central portion of each portion. The side of the sputter surface of each of the test pieces was ground. After grinding with water-resistant paper of #180~#4000, polishing is performed with abrasive grains of 3 μm to 1 μm.

Next, etching is performed to the extent that the grain boundary can be seen by an optical microscope. Here, the etching liquid is a mixture of hydrogen peroxide water and ammonia water, and immersed at room temperature for 1 to 2 seconds to reveal grain boundaries. Next, for each sample, optical display The micromirror takes a photo with a magnification of 30 times.

In each of the photographs, a line segment of 60 mm was drawn in a grid shape at intervals of 20 mm in a total of four vertical and horizontal directions, and the number of crystal grains cut by each straight line was calculated. The crystal grains at the end of the line were counted as 0.5. The average slice length: L (μm) was determined by L = 60000 / (M.N) (where M is a real magnification and N is the average of the number of crystal grains cut). The average slice length obtained from: L (μm), with d = (3/2). L calculates the average particle diameter of the sample: d (μm). The evaluation results are shown in Table 2.

(The presence or absence of a segregation portion having a particle diameter of 1 μm or more)

The sample piece was prepared in the same manner as in the measurement of the crystal grain size, and a photograph was taken at a magnification of 1500 times using an optical microscope to confirm the presence or absence of a segregation portion having a particle diameter of 1 μm or more. The evaluation results are shown in Table 2.

Moreover, FIG. 1 shows an example of the observation result of the segregation section. Fig. 1(a) shows the observation results of the Ag alloy sputtering target of Example 1 of the present invention, and Fig. 1(b) shows the observation results of the Ag alloy sputtering target of Example 26 of the present invention. The segregation portion in the Ag alloy sputtering target of Example 1 of the present invention was observed as a black spot.

(The number of abnormal discharges at the beginning of use)

The Ag alloy sputtering target of the above inventive examples and comparative examples was welded to a backing plate made of oxygen-free copper using indium solder to prepare a target composite.

The target composite is mounted on a general magnetron sputtering apparatus, and after exhausting to 5 × 10 ^-5 Pa, the pressure of Ar gas is 0.5 Pa, the power is supplied: DC 1000 W, and the distance between the target substrates is 70 mm. Perform sputtering. The number of abnormal discharges at the time of sputtering was measured by the arc calculation function of a DC power source (RPDG-50A) manufactured by MKS Instruments Co., Ltd., and the number of abnormal discharges one hour after the start of discharge was measured. The evaluation results are shown in Table 2.

(The number of abnormal discharges after long-time sputtering)

Repeat the exchange of 4 hours of splash and anti-plate, and consume the target by intermittent sputtering for 20 hours. Subsequently, sputtering was further carried out under the above conditions, and the number of abnormal discharges generated one hour after the consumption (20 hours of sputtering) was measured. The evaluation results are shown in Table 2.

(The ratio of the change rate of the sputtering rate before and after the long-term sputtering)

After the initial sputtering rate was measured, the exchange of the empty sputtering and the anti-plate was repeated for 4 hours as described above, and the target was consumed by sputtering for 20 hours. Subsequently, sputtering was further carried out, the sputtering rate was measured, and the variation ratio of the sputtering rate was evaluated by the following formula. The evaluation results are shown in Table 2.

Sputter rate change ratio = rate after long-term sputtering / rate of initial use

(Change rate of film composition before and after long-term sputtering)

The composition of the film-forming Ag alloy film at the initial stage of use was measured. The film composition was measured by forming an Ag alloy film into a film of 3000 nm, and measuring the film by ICP spectrometry. Subsequently, the exchange of the sputter and the anti-plate was repeated for 4 hours as described above, and the target was consumed by sputtering for 20 hours. Subsequently, sputtering was carried out to measure the composition of the formed Ag alloy film, and the film was evaluated by the following formula. The rate of change in composition. The results are shown in Table 2.

Rate of change of film composition (%) = (composition of additive element A after long-term sputtering / composition of additive element A at the beginning of use) × 100

Further, the added element A is the one having the largest change rate among the added elements.

<Ag alloy film>

The Ag alloy sputtering target of the above-described inventive examples and comparative examples was mounted on a sputtering apparatus, and an Ag alloy film was formed under the following conditions.

Substrate: Washed glass substrate (EAGLE XG, manufactured by Conning, thickness 0.7mm)

The degree of vacuum reached: 5 × 10 ^-5 Pa or less

Use gas: Ar

Gas pressure: 0.5Pa

Sputtering power: DC 200W

Target/substrate distance: 70mm

(Measurement of film thickness)

A cross section polisher (CP) was used to prepare an observation sample, and the cross section of the Ag alloy film was observed by an electron microscope (TEM) to calculate the film thickness of the Ag alloy film. The membrane construction is shown in Table 3.

(constant temperature and humidity test)

The filmed Ag alloy film was placed in a constant temperature and humidity chamber at a temperature of 85 ° C and a humidity of 85% for 250 hours.

(sheet resistance value)

The sheet resistance value R _S0 of the Ag alloy film after film formation and the sheet resistance value R _S1 of the Ag alloy film after the constant temperature and humidity test were measured by a four-probe method of a Mitsubishi chemical resistance measuring device ROLESTA GP. Further, the rate of change (%) before and after the constant temperature and humidity test was calculated by the following formula. The measurement results are shown in Tables 3 and 4.

Rate of change (%) = (R _{S1 -} R _S0 ) / R _S0 × 100

(visual transmittance)

The measurement of the transmittance of the Ag alloy film was carried out by using a spectrophotometer (U-4100, manufactured by Hitachi High-Technologies Corporation), and the transmittance of the substrate on which the film was not formed was set to 100, and the relative transmittance of the film was measured. Evaluation. The transmittance spectrum %T is measured in the range of 780 to 380 nm, and the Y value of the light source D65 and the XYZ color system of the field of view of 2° is calculated from the spectrum using a color calculation program (according to JIS Z 8722), and the calculated value is used as the calculated value. Visual transmittance.

Such as the visual sense of the Ag alloy film after forming the aforesaid measured T ₀ and a transmittance depending on a sense of the Ag alloy film after the constant temperature and humidity test transmittance T _1. Further, the amount of change T ₁ -T ₀ before and after the constant temperature and humidity test was calculated. The measurement results are shown in Tables 3 and 4.

(visual absorption rate)

The absorbance of the Ag alloy film is in the range of 780 to 380 nm. The transmittance spectrum %T measured by the spectrophotometry described above and the reflectance spectrum %R were measured, and the absorption spectrum spectrum %A was calculated from the spectrum of the following equation.

%A=100-(%T+%R).

The Y value of the light source D65 and the XYZ color system of the field of view of 2° was calculated from the spectrum using a color calculation program (according to JIS Z 8722), and the calculated value was taken as the visual absorption rate.

Such as the visual sense of the Ag alloy film after forming the aforesaid absorption measured luminosity of the Ag alloy film ratio after humidity testing A ₀ and absorbance A _1. Further, the amount of change A ₁ -A ₀ before and after the constant temperature and humidity test was calculated. The measurement results are shown in Tables 3 and 4.

(Appearance observation after constant temperature and humidity test)

The appearance of the Ag alloy film placed in a constant temperature and humidity layer at a temperature of 85 ° C and a humidity of 85% for 250 hours was visually observed. As shown in Fig. 2(a), the Ag alloy film in which no speckle-like discoloration was observed on the surface of the film was evaluated as "A". As shown in Fig. 2(b), a spot-like discolored Ag alloy was observed on the surface of the film. The film was evaluated as "B". The evaluation results are shown in Table 4.

(sulfur resistance test)

The film-forming sample was immersed in a 0.01% by mass aqueous sodium sulfide solution at room temperature for 30 minutes, taken out from the aqueous solution, and sufficiently washed with pure water, and then sprayed with dry air to remove water. The sheet resistance and the transmittance were measured in the same manner as described above, and the sulfurization resistance was evaluated from the amount of change in transmittance and the rate of change in sheet resistance. The evaluation results are shown in Table 5.

(resistance to salt water test)

The film-forming sample was immersed in a 5% NaCl aqueous solution at room temperature for 24 hours, taken out from the aqueous solution, and sufficiently washed with pure water, and then sprayed with dry air to remove water. With respect to these samples, the sheet resistance and the transmittance were measured in the same manner as described above, and the salt water resistance was evaluated from the amount of change in transmittance and the rate of change in sheet resistance. The evaluation results are shown in Table 5. Further, in Table 5, the immersion in a 5% NaCl aqueous solution and the disappearance of the film were expressed as "unable to measure".

The Ag alloy film of Comparative Example 101 in which the Ag alloy sputtering target of Comparative Example 1 having a Sn content is less than the range of the present invention was used, and the temperature was constant. The visual transmittance and the visual absorption rate after the wet test were largely deteriorated, and the environmental resistance was insufficient.

The Ag alloy film of Comparative Example 102 in which the Ag alloy sputtering target of Comparative Example 2 having a content of Sn was used in a larger amount than the range of the present invention had a high sheet resistance and a high apparent absorption rate after film formation, and electrical characteristics and optical characteristics. insufficient.

The Ag alloy film of Comparative Example 103 in which the Ag alloy sputtering target of Comparative Example 3 having a Cu content less than the range of the present invention was formed, the sheet resistance of the Ag alloy film after the constant temperature and humidity test was remarkably increased, and spots on the surface of the film were generated, and environmental resistance was observed. insufficient.

The Ag alloy film of Comparative Example 104 in which the Ag alloy sputtering target of Comparative Example 4 having a Cu content was more than the range of the present invention was used, and the sheet resistance after film formation was high, and electrical characteristics were insufficient.

The Ag alloy film of Comparative Example 105 in which the Ag alloy sputtering target of Comparative Example 5 having a Ti content is more than the range of the present invention has a high sheet resistance after film formation, and has low visual transmittance, electrical characteristics, and optical properties. Insufficient characteristics.

On the other hand, the Ag alloy film formed by using the Ag alloy sputtering target of the present invention is excellent in electrical characteristics, optical characteristics, and environmental resistance.

Next, in the Ag alloy sputtering target of Examples 20 to 23, 30, and 31 of the present invention, the total content of Na, Si, V, Cr, Fe, and Co in the impurity element exceeds 100 ppm by mass, and the number of abnormal discharges is large.

Further, in the Ag alloy sputtering target of Examples 11 to 16, the content of each of Na, Si, V, Cr, Fe, and Co in the impurity element exceeded 30 ppm by mass, and the number of abnormal discharges was slightly increased.

On the other hand, the total content of Na, Si, V, Cr, Fe, and Co in the impurity element is 100 ppm by mass or less, and the content of each of Na, Si, V, Cr, Fe, and Co is also 30 mass ppm or less. The Ag alloy sputtering target of the inventive example has a small number of abnormal discharges.

Further, the Ag alloy sputtering target of the inventive examples 28 and 29 having an average crystal grain size of the sputtering surface exceeding 200 μm has a large number of abnormal discharges after long-time sputtering.

On the other hand, in the Ag alloy sputtering target of the present invention having an average crystal grain size of 200 μm or less on the sputtering surface, the number of abnormal discharges after long-time sputtering is small.

Further, the Ag alloy sputtering target of the inventive examples 1 to 23 having a segregation portion having a particle diameter of 1 μm or more was observed to have a large change ratio of the sputtering rate after the long-time sputtering and a change rate of the film composition.

On the other hand, in the Ag alloy sputtering target of the present invention which does not observe the segregation portion having a particle diameter of 1 μm or more, the change ratio of the sputtering rate after the long-time sputtering and the rate of change of the film composition are suppressed.

Further, the Ag alloy sputtering target of Inventive Examples 17 to 19, 25, 27, 29, and 31 containing Ti was found to have excellent sulfuric acid resistance and salt water resistance.

As a result of the above-described confirmation experiment, it was confirmed that an Ag alloy sputtering target and an Ag alloy film of an Ag alloy film excellent in film formation electrical properties, optical properties, and environmental resistance can be provided according to the examples of the present invention.

[Industrial Applicability]

According to the Ag alloy sputtering target of the present invention, a film can be formed An Ag alloy film excellent in properties, optical properties, and environmental resistance can suppress occurrence of abnormal discharge or the like at the time of film formation. Moreover, the Ag alloy film formed by the Ag alloy sputtering target of the present invention is suitable for an electronic device such as an organic EL device because it has excellent conductivity (electrical properties).

Claims (11)

An Ag alloy sputtering target characterized by containing Sn in a range of 0.1 at% or more and 3.0 at% or less, Cu in a range of 1.0 at% or more and 10.0 at% or less, and the balance being Ag and inevitable impurities. The composition of the composition. The Ag alloy sputtering target according to claim 1, wherein a total content of Na, Si, V, Cr, Fe, and Co among the unavoidable impurities is 100 ppm by mass or less. The Ag alloy sputtering target according to claim 1 or 2, wherein each of the inevitable impurities contains Na, Si, V, Cr, Fe, and Co in an amount of 30 ppm by mass or less. The Ag alloy sputtering target according to any one of claims 1 to 3, wherein the average crystal grain size of the sputtering surface is 200 μm or less, and the particle size of the segregation portion formed of Cu, Sn or the intermetallic compound Less than 1μm. The Ag alloy sputtering target according to any one of claims 1 to 4, further comprising Ti in a range of 0.1 at% or more and 3.0 at% or less. A method for producing an Ag alloy sputtering target, which is the method for producing an Ag alloy sputtering target according to claim 4, characterized in that it has a melting casting step of forming an Ag alloy ingot, and the obtained Ag alloy ingot is rolled. The rolling step and the heat treatment step of performing heat treatment after rolling, and the heat treatment temperature in the heat treatment step is in the range of 650 ° C to 750 ° C. An Ag alloy film characterized by containing Sn in a range of 0.1 at% or more and 3.0 at% or less, and 1.0 at% or more at 10.0% Cu is contained in the range of at least atomic %, and the remainder is composed of Ag and unavoidable impurities. The Ag alloy film of claim 7 has a visual transmittance of 70% or more and a visual absorption rate of 10% or less. The Ag alloy film of claim 7 or claim 8 has a sheet resistance value of 40 Ω/□ or less. The Ag alloy film according to any one of claims 7 to 9, which has a film thickness of 4 nm or more and 10 nm or less. A method for producing an Ag alloy film, which is formed by using an Ag alloy sputtering target according to any one of claims 1 to 5.